Technical Abstract:
The soybean aphid, APHIS GLYCINES Matsumura, was recently introduced from Asia into North America (NA) where it has become a serious pest of soybeans. This invasive pest spread rapidly throughout the north central United States and southern Canada since its discovery in 2000. We examined 593 individuals obtained from 24 different geographic collections in the USA, Korea, China, and Japan using eight microsatellite loci. Based on analysis of multilocus genotypes, gene diversity and the number of alleles in NA averaged 0.40 and 2.70, whereas in Asia they averaged 0.55 and 4.32, respectively. The factorial correspondence analysis revealed that some Korean populations were closely related to the NA populations. Structure analysis resulted in two conspicuous clusters, NA and Asia, as the most likelihood number of clusters (K=2). Bayesian assignment tests indicated that populations from Osan and Milyang in Korea were most similar to the NA populations. A bottleneck test did not indicate the occurrence of a significant genetic bottleneck in these populations.